That is THE question of the day.
It is not clear to me either why his resignation should be a bargaining chip that he can use to secure a sweetheart deal with the prosecutor. Personally, I hope he stays in office the rest of the year so that we can talk endlessly about the Culture of Corruption and let the Dems twist in the wind a bit. In fact, Spitzer has taken that issue off the table for this years election cycle. The Dems have lost a big issue that they successfully ran on in 2006. Life isn't good yet but it is getting better.
Until I stop and remember that McCain is the Republican nominee.